Refrigerant compressor having built-in liquid return protection



Dec. 30, 1.969 'w, AYUNG 3,486,687

, v REFRIGERANT COMPRESSOR HAVING BUILT-IN LIQUID RETURN PROTECTIONFiled June 19, 1968 INVENTOR= ROBERT w. AYLING, BYW 7. WM

ATTORNEY United States Patent O US. Cl. 230-206 8 Claims ABSTRACT OF THEDISCLOSURE A hermetic refrigerant compressor with a vertical crankshafthas an outer shell with an oil sump in its bottom, and has a suction gastube with an outlet in its upper portion. A cylindrical inner shell issupported at its bottom by a crankcase wall of the compressor, andextends in heat exchange contact with the cylinder heads and the muffierof the compressor. Refrigerant liquid flowing from the suction gasoutlet drains into the inner shell, and is evaporated to prevent it fromaccumulating in the oil sump and diluting the oil. The inner shell has asmall oil bleed hole in its bottom.

BACKGROUND OF THE INVENTION The field of the invention is hermeticrefrigerant compressors having vertical crankshafts, such as aredisclosed in my US. Patents Nos. 3,171,588 and 3,259,307. Suchcompressors have oil sumps in their bottoms, and have suction gas tubeswith outlets in their upper portions. Oil and any refrigerant liquid inthe suction gas flow into the oil sumps. Under some conditions such asfloodback, and reversal of a heat pump in which such a compressor isused, a substantial quantity of refrigerant liquid can drain into theoil sump, and so greatly dilute the lubricating oil that the bearings ofthe compressor may be damaged. This invention prevents substantialquantities of refrigerant liquid from draining into such an oil sump byevaporating it within an inner shell around and in contact with heatedcomponents of the compressor.

SUMMARY OF THE INVENTION A hermetic refrigerant compressor havingiavertical crankshaft, has an outer shell with an oil slump in its bottom,and a suction gas outlet in its upper portion. The compressor has acylindrical crankcase wall just above the oil sump, and fitted to thiswall is the bottom of an inner shell having an open top just below thesuction gas inlet. The inner shell extends around and in heat exchagecontact with the cylinder heads and the muffler of the compressor, andhas a small oil drain hole in its bottom. Refrigerant liquid and oil inthe suction gas flow from the suction gas outlet into the inner shell,and are heated by the contact of the latter with the crankcase wall, thecylinder heads and the mufiler so that the refrigerant liquid isevaporated and prevented from diluting the oil in the oil sump. The oildrain hole permits oil to drain from the inner shell into the oil sumpbut is too small to permit any substantial flow of refrigerant liquid.

DESCRIPTION OF THE DRAWING The drawing is a side view of a refrigerantcompressor embodying this invention, with the inner and outer shellsshown in cross-section.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring tothe drawing, a generally cylindrical outer shell 10 has an upper portionextending around a motor 3,486,687 Patented Dec. 30, 1969 ice cover 12,and has a lower portion with an oil sump 15 in its bottom. An electricmotor (not shown) within the cover 12, has a rotor (not shown) attachedto crankshaft (not shown) of the compressor. The compressor hascylinders with heads 17, 18 and 19, and another cylinder with a head(not shown) opposite the head 18, and has a cylindrical crankcase wall21 below the cylinder heads. Discharge gas tubes 23, 24 and 25 extendfrom the respective cylinders into a mufller 27 which is connected to adischarge gas tube 30 extending around the motor cover 12, and having avertically extending portion 31 for connection to a condenser coil (notshown). A suction gas tube 32 from an evaporator coil (not shown)extends through the upper portion of the shell 10, and has a divergingoutlet 34 containing a filter (not shown). The motor cover 12 has abracket 38 connected thereto by studs 37. The bracket 38 is attached toone end of coiled spring 39, the other end of which is attached tobracket 40 which is attached to the shell 10. Bearing housing 41 extendsbelow the crankcase wall 21, and has a spiral spring 43 therearound. Thespring 43 is within cup 42 in contact with the bottom of the latter. Thecup 42 is on the bottom of the shell 10.

The construction described so far in connection with the drawing isgenerally that of my previously mentioned Patent No. 3,171,588 which maybe referred to for explanation of the operation of the compressor. Thisinvention adds to the compressor, a cylindrical inner shell 50 having acentral opening in its bottom, and having a cylindrical bottom portion51 extending around such opening, and force fitted to the crankcase wall21. The shell 50 also extends in heat exchange contact with the cylinderheads 17, 18 and 19, and in heat exchange contact with the previouslymentioned other cylinder head (not shown), and also extends in heatexchange contact with the muffler 27. The shell 50 has an open upper endbelow the suction gas tube outlet 34. The bottom of the shell 50 hasjust above its bottom portion 51, a small oil bleed hole 52. The hole 52is too small to permit the flow of any substantial amount of refrigerantliquid which may be within the shell 50, into the oil sump 15.

Oil and any refrigerant liquid within the suction gas flow through thesuction gas tube outlet 34 into the inner shell 50 which is seen tooperate as an accumulator. The refrigerant liquid flowing into the shell50 is evaporated by heat from the mufiler 27, the cylinder heads 17, 18and 19, the crankcase wall 21, and the other heated components of thecompressor such as the discharge gas tubes 23, 24, 25 and 30 which theinner shell 50 surrounds. The drain hole 52 permits oil to drain intothe oil sump 15, but is too small to permit any substantial quantity ofrefrigerant liquid which may be within the inner shell at times,including start-up, to flow into the sump 15.

Thus, the compressor is seen to have built-in protection againstdilution of its lubricating oil, and the resulting damage to itsbearings.

I claim:

1. In a refrigerant compressor having an outer shell with an oil sump inits bottom, and a suction gas outlet in its upper portion; saidcompressor having, and said shell extending around, a crankcase having awall near and above said bottom, cylinders having heads, above andjoined to said crankcase, a muffler above and connected to saidcylinders, a discharge gas tube above and connected to said mufiler; theimprovement comprising an inner shell supported within said outer shellaround said wall, said heads, said muffler, and around said tube, saidinner shell having an open top below and arranged to receive refrigerantliquid and oil from said outlet, having a bottom around said wall withan oil drain hole therein, said bottom of said inner shell being in heatexchange contact with said wall.

2. The improvement claimed in claim 1 in which said 8, The improvementlai d i laim 1 i whi h aid inner shell is in heat exchange contact withsaid heads. inner shell is in heat exchange contact with said mufller.

3. The improvement claimed in claim 2 in which said inner shell is inheat exchange contact with said muffler. References Cited I 4. Theimprovement claimed in claim 1 in which said 5 UNITED STATES PATENTSlnner shell is supported by said wall.

5. The improvement claimed in claim 4 in which said 31065901 11/1962Nqubauer 230 58 inner shell is in heat exchange contact with said heads.3,162,360 12/1964 Pnvon et 230-406 6. The improvement claimed in claim 5in which said inner shell is in heat exchange contact with said mufiler.ROBERT WALKER Pnmary Exammer 7. The improvement claimed in claim 4 inwhich said US, Cl, X,R inner shell is in heat exchange contact with saidmuffler. 230-232

